Gas turbines

ABSTRACT

A gas turbine unit comprising a turbine fed with hot gas through a furnace to which air is fed by a compressor. The turbine rotor blading is discontinuously cooled by alternating passage into a hot flow and a cold flow. To this end, the turbine comprises separate feed sector areas respectively receiving the hot gas flow emerging from the furnace and a colder flow. The colder flow is a flow of air which is fed directly from the compressor rotor blading to the turbine rotor blading.

1 United States. Patent 1 1 11 1 3,731,486 Poulain et a1. 1 1 May 8 1973 [54] GAS TURBINES 3,271,952 9/1966 Silvern et a1 60/3966 t 2,656,096 10/1953 Schwarz 1 v ..60/39.66 [75] Invemms' f f 1,741,957 12 1927 Scdlmcir ..60/39.l9

Jacques Plerre Chaboseau, L1me11- Brevannes, both of France FOREIGN PATENTS OR APPLICATIONS Assigneer Sociele Paris, France 215,484 10 1941 Switzerland ...1..60 39.19

[22] Filed: May 24, 1971 Przmary Examiner-Carlton R. Croyle 1 PP 4 Assistant ExaminerWarren Olsen Related [1.8. Application Data Atwmey wl]ham Dame [63] Continuation-in-part of Ser. No. 73,895, Sept. 21, [57] ABSTRACT 1970 abandoned A gas turbine unit comprising a turbine fed with hot F A P D gas through a furnace to which air is fed by a com- [301 orelgn pphca y ata pressor. The turbine rotor blading isdiscontinuously Apr. 20, 1971 France ..7l13925 ooled by alternating passage into a hot flow and a cold flow. To this end, the turbine comprises separate 1 feed sector areas respectively receiving the hot gas [51] lnt.Cl........ flow emerging from the furnace and a colder flow. [58] Field Of Search ..60/39.19, 39.51 R, The colder flow is a flow of air which is fed directly 39-65 from the compressor rotor blading to the turbine rotor blading. [56] References Cited 21 Claims, 15 Drawing Figures UNITED STATES PATENTS 1,375,931 4/1921 Rateau ..60/39.19

Patented May 8, 1973 9 Sheets-Sheet 1 Patented May 8, 1973 3,731,486

9 Sheets-Sheet 2 Patented May 8, 1973 3,731,486

9 Sheets-Sheet 4.

Patented .May 8, 1973 9 Sheets-Sheet 7 kmw m Qt

9 Sheets-Sheet 8 Patented May 8, 1973 v 3,731,486

9 Sheets-Sheet 9 GAS TURBINES This is a continuation-in-part of our copending application Ser. No. 73,895 filed on Sept. 21, 1970, now abandoned.

The invention relates to gas turbine units comprising a compressor which discharges air into a furnace or combustion chamber to perform combustion of a fuel so as to generate hot gas for feeding a gas turbine. The invention is concerned with improvements enabling to increase the inlet gaz temperature to the turbine.

Gas turbine units are currently used in industry, and it has been known for long that it would be an advantage if the inlet temperature to a gas turbine could be very substantially increased. Such a capability would result, in fact, not only in improving the overall efficiency of a gas turbine unit, but also in increasing to a large extent the specific output thereof or reducing the floor space, weight and cost of a gas turbine unit for a given output. The combination of both these advantages would enable to promote the gas turbine technique and to extend its application field.

The development of high temperature gas turbine units is unfortunately subject tolimitations, at least if the usual structure of these machines is not to be modified. The most important of these limitations, and the only critical one at the present time, is concerned with high temperature strength of the rotor portion that works at the highest temperature level in the unit. This rotor portion has to take a system of stresses of high value due to centrifugal effects, thermal non-uniformity and, to a lesser extent, aerodynamic forces that produce the turbine torque. It is known moreover that the mechanical properties of the metals rapidly fall with temperature increasing beyond a temperature threshold, and that the bearable stress becomes then dependent on its application time. For a given material which must have a given lifetime and which is subjected to a system of stresses as men'tionedabove, there is a limit temperature which cannot be exceeded.

Beside the search for materials, metallic or not, capable of bearing higher temperatures, it has already been proposed, in order to obviate the abovesmentioned limitations, to cool the elements which are exposed m high temperature so as to keep them at a lower thermal level than the environment. Two cooling processes have been largely explored, namely cooling by an inter- In the first mentioned process, the intermediary liquid may be an organic or a mineral fluid, or even a molten metal. The liquid is sealed in every blade, the root portions thereof forming heat exchangers, and the liquid can be irculated by thermosiphon effect.

Direct cooling by air has given rise to numerous applications generally distinguished among themselves according to the type of cooling used, i.e., by convection, impact, air film or transpiration When cooling by convection, the air circulates within the turbine blades in one or more runs within channels, radial or not, and is ejected through blade tips. FIGS. 1 and la of the accompanying drawings show as an example, respectively in axial section and in enlarged cross section, a turbine rotor blade 1 provided with channels 2 in which air circulates. The air is introduced through the hollow root portion 3 of the-blade, enters the channels 2 through openings 2a and is discharged through openings 2b in the blade tip.

When cooling by impact, jets of air are projected onto the internal wall surface of the blade to be cooled. When cooling by air film, the air is ejected along the blade contour, in the direction of flow of the hot gas, through separate openings and forms a protecting air film. In the transpiration cooling process, the blade is made of porous material and air is continuously exuded all around the blade contour. FIG. 2 of the accompanying drawings is a view similar to FIG. la, showing a hollow blade 4 which is cooled by convection, impact and air film altogethen'A perforated partition 4a defines a chamber 4d within an inner recess 45 in the blade, near the leading edge 40 thereof, and the chamber 4d is provided with openings 4e. The remaining portion of the recess 4b is separated from the blade wall by a further partition if whose front end is spaced from wall 4a, so that a portion of the air admitted'in this recess 4b flows as shown by arrows 5 to cool theinternal surface of the blade wall by convection, and is discharged through an ejection slot 5a in the trailing edge of the blade. As shown by arrow 5b, a further portion of the air flows through the perforated partition 4a to cool the leading edge 4c by impact, and is discharged out of the chamber 4d as shown by arrows 50 to flow along the external surfaces of the blade and form a protecting air film.

The cooling methods described above present many disadvantages, the most important of which are as follows they involve technological difficulties,

their cost is high due to the complexity, not only of the blades themselves, but also of the air supply means which may require very efficientseals, in some cases,

they increase the centrifugal mechanical stress level by concentration of stresses and possiblethey require alteration the blade profiles, so that the same depart from the optimal aerodynamic forms, and

the cooling channels, which are very narrow, can

be choked up by dust or impurities.

' The present invention contemplates to eliminate these drawbacks by discontinuously cooling the rotor of a high temperature gas turbine by alternate ction of a hot flow and a cold flow of gas.

To this end, in a form of the invention, a gas turbine is fed through distinct sector areas respectively receiving a hot gas flow originating from a furnace and a flow which is colder. In the rotation of the turbine rotor, the

blades of the same pass successively through the hot flow andthe cold flow, so that their temperature settles at an intermediary value between the hot flow temperature and the cold flow temperature. The cooling which they expand, this enabling these members to be kept at a moderate mean temperature in spite of the very high thermal level of the combustion gas.

Preferably the cold flow is supplied by the compressor.

The invention mainly applies to the gas turbine units comprising one or more free shaft lines, but can also be applied to gas turbine units supplying working power.

In an embodiment of the invention, the hot and cold flows or streams are separated by solid partitions upstream and downstream of the turbine. Degradation of the engine thermodynamic cycle, which would result from mixing the hot flow and cold flow, is thus avoided.

In a further embodiment of the invention, losses which would result from successive conversions of kinetic energy of the cold flow into pressure and vice versa are eliminated by providing a direct passage from the outlet of the compressor rotor blading to the inlet of the turbine rotor blading, without the cold flow passing through any distributor or volute chambers. The outlet conditions of the compressor rotor blading must of course be adapted to the inlet conditions of the turbine rotor blading, and the man of the art knows that this requirement is spontaneously fulfilled in the case of engines of the radial-flow type forming a free shaft line. In the case of engines of other types, for example of the axial-flow type, the adjustment of the above mentioned conditions can be carried out by a suitable layout of the turbine and compressor bladings as known in the art.

In a practical embodiment, a gas turbine unit comprises a free shaft line supporting a centrifugal compressor wheel which delivers air into a furnace or combustion chamber through the intermediary of an outlet diffuser, and a centripetal turbine wheel fed with hot gases supplied by the furnace through the intermediary of a volute chamber and an inlet distributor, while a conduit directly connects an outlet sector of the compressor wheel blading to an inlet sector of the turbine wheel blading in order to feed the latter with cooling air. Each of'the channels designed by the turbine wheel blading is thus fed alternately with hot gases and with cold air.

However, since the cold air has a higher density than the hot gases, its presence in the channels of the turbine wheel modifies the distribution of the centrifugal forces within the gaseous flow, and consequently affects the equilibrium conditions of that flow. The man of art will be able, by applying the methods of fluid mechanics, to verify by calculation that the presence of the cold air slows down the flow in the channels. Calculation also shows that if, as is currently the case in a centrifugal blading associated with a centripetal blading, the compressor wheel is a radial wheel, then the air which leaves it to enter directly the turbine wheel will generally be at an insufficient static pressure to overcome the centrifugal forces in the channels of the said turbine wheel during the transition phase, and may consequently create difficulty in the separation of the hot and cold flows at the outlet of the turbine wheel driving the compressor.

According to one embodiment of the invention, this risk is eliminated and the flow of the cold air in the channels of the turbine wheel is accelerated by virtue of means which produce, at the outlet of the blading of the centrifugal wheel, a static pressure greater than that which is produced at the outlet of the blading of the radial wheel giving the same compression ratio (as total pressure). For example, the compressor may comprise, upstream of the centrifugal wheel, an axial flow compression stage, the rotor of which is supported by the free shaft line which supports the said centrifugal wheel and the turbine wheel. As a variant, the classic centrifugal wheel having radial tip blades may be replaced by a centrifugal wheel having backwardly curved blades. Both these means may also be used simultaneously. It is self-evident that to replace the axial flow stage by a different type of compressor would not involve a departure from the spirit of the invention.

The centrifugal compressor wheel and the centripetal turbine wheel are advantageously placed back to back, with their bladings separated by median partition means. The median partition means may extend radially as far as the periphery of the bladings. The conduit directly leading the cooling air from the compressor outlet to the turbine inlet is then a segment of a torus which straddles the median partition means However, this conduit may also be realized at least partly through the median partition means. In one embodiment, the compressor and turbine bladings are mounted in back-to-back relation on either side of a disc-shaped rotatable partition member, and extend radially beyond the rotatable partition member (which is part of the current practise for the man of art) and their outer portions external to the rotatable partition member are separated by a sector shaped stationary partition member which extends between the outlet diffuser of the compressor and the inlet distributor of the turbine, but communicate freely between themselves in the sector external to the said stationary partition member where the cooling air coming from the compressor is led and introduced into the turbine.

The description which follows in regard to the accompanying drawings, given as a non limitative example, will convey an understanding of the advantages of the invention and the art for carrying it out.

In the drawings:

FIGS. 1, la and 2 are explanatory sketches which were described on in the introduction of the present description;

FIG. 3 is a schematic axial section of a conventional gas turbine unit of the radial-flow type, and FIG. 3a is an enlarged end view of the turbine with the casing being supposed transparent;

FIG. 4 is a schematic axial section of a conventional gas turbine of the radial-flow type comprising a free shaft line and a shaft line supplying working power;

FIG. 5 is a view similar to FIG. 4, showing a gas turbine unit comprising a cooling means of the invention, and FIGS. 5a and 5b are respective enlarged end views of the turbine and the compressor of the unit, the casing thereof being supposed transparent;

FIG. 6 is a view similar to FIG. 5 showing a gas turbine unit, the compressor of which comprises an axial stage upstream of a centrifugal wheel.

FIG. 7 is a view similar to FIG. 5b, showing a centrifugal wheel with backwardly inclined blading.

FIG. 8 is a view similar to FIG. 6, showing a centrifugal compressor wheel placed back to back with a centripetal turbine wheel, with a means having a cut-out sector partition to form a direct passage from the compressor wheel to the turbine wheel;

FIG. 9 is a schematic axial section of a gas turbine unit of the axial-flow type comprising a cooling means of the invention; g

FIG. is a schematic axial section of a gas turbine unit of the radial-flow type comprising a low pressure body and a high pressure body, the high pressure turbine being cooled by a means of the invention; and

FIG. 11 is a view similar to FIG. 10, showing a gas turbine unit comprising a heat exchanger.

FIGS. 3, 3b and 4 show conventional gas turbine units to establish a background needed to understand the invention. The units shown on FIG. 3 comprises a centrifugal compressor wheel 6 and a centripetal turbine wheel 7 mounted on a same shaft 8 carried by bearings 9 and supplying a working power to a coupling member 10 through a gear reducer 11. The compressor wheel 6 draws in fresh air from atmosphere at 12, compresses it and discharges it through guide vanes 26 into a volute chamber 13 communicating through a conduit 14 with a furnace 15 provided with a burner 16. The hot gas produced in a known way in the furnace is forwarded through a conduit 17 and a turbine inlet volute chamber 18 to a distributor 19 (FIG. 3a) which feeds the blading 20 of the turbine wheel 7. The hot gas is expanded in the turbine wheel and discharged into an outlet conduit 21.

It will be noticed that, in such a gas turbine unit, the compressor discharges compressed air over the whole of its circumference towards the guide vanes 26, the volute chamber 13 and the furnace, and the hot gas is injected over the whole turbine periphery through the volute chamber 18 and the distributor 19. The guide vanes 26 and the volute chamber 13 together form what will be called hereafter a compressor diffuser 26, 13.

This remark applies to the gas turbine unit of FIG. 4, in which the elements performing like functions as in FIG. 3 are designated by the same reference numbers plus the aliphabetical suffix a. The unit of FIG. 4 differs I only fromthat of FIG. 3 in that the wheels of the comleading to the atmosphere.

FIGS. 5, 5a and 5b, in which the elements performing like function as in FIG. 4 are designated by the same reference numbers plus the suffix b, show a gas turbine unit similar to that of FIG. 4 but modified to incorporate a cooling means according to the invention. The compressor 6b discharges compressed air into the diffuser 26b, 13b (FIG. 5b) only on a sector or segmental portion of its circumference, limited by partitions 27 and 28. The distributor 19b of the turbine 7b (FIG. 5a) receives the hot gas from the volute chamber 18b only on a sector or segmental portion of its circumference limited by the same partitions 27 and 28.In the remaining sector region, comprised between these partitions, the compressor wheel outlet is directly connected to the turbine wheel inlet through a conduit 29 in the form of a segment of a torus. The blading of the turbine wheel 7b is thus fed by a device 18b, 19b, 29 having a first outlet sector 19' (occupied by the distributor 19b and limited by the partitions 27, .28) which is fed with hot gases, and a second outlet sector 29' (occupied by the conduit 29 between the partitions 27, 28) which is fed with air. Moreover, the annular cross-section 30 at the inlet of the conduit 21b, receiving the hot gas discharged from the turbine wheel 7!) is discontinued by two partitions 31, 32 (see FIG. 5a) linked to an auxiliary conduit 33 (FIG. 5) leading to the atmosphere at 34. The partitions 31, 32 define in the annular passage 30 a sector area 35 which is staggered forwardly relative to the torus segment conduit 29, in the direction of rotation of the turbine wheel shown schematically by arrow F (see FIG. 5a).

By comparing FIGS. 5 and 5a to FIG. 4 and FIG. 3a, it can be seen that the elements 26b, 19b, 29 and 33 are characteristic of the invention. In FIGS. 5 and 5a, the cold flow discharged by the compressor 66 is depicted by dotted shading. The cold air flow discharged by the compressor 6b is divided into two streams one of which is conventionally fed through the: diffuser 26b, 13b to the furnace 15b, the hot gases generated therefrom feeding the turbine distributor 19b oneither sides of partitions 27 and 28. The other partial flow is not heated in the furnace and flows through neither the diffuser 26b, 13b nor the distributor 19b, but is bypassed through the direct linking conduit 29 to and through the turbine wheel 7b and is discharged to the atmosphere through the discharge conduit 33 without being mixed with the hot flow from the furnace. It can therefore be seen that the turbine 7b passes through a relatively cool air region in the sector portion of the turbine which is on the right of FIG. 5a (and schematically shown at the bottom of FIG. 5), as well as through a hot gas region receiving gas from the furnace in the remaining peripheral portion of the turbine. Due to the high rotating speed of the turbine wheel 7b, the turbine wheel quickly assumes all its points a mean temperature inter-mediate the respective temperatures of the hot and cold streams contacting it. In FIG. 5b, a rrowsf schematically show the path'of the air dischargedthrough the compressor wheel 6b into the guide vanes 26b and therefrom into the volute chamber 13b leading to the furnace, and arrows f schematically show the path of the air discharged into the direct linking conduit 29 and therefrom into the corresponding turbine wheel sector region; the arrows f are also shown in FIG. 5a. I

In FIG. 5a, the broken lines 36 schematically illustrate an ideal separation surface between the volume occupied by the relatively cold air (shown in dotted shading) and the volume occupied by the hot gas. It is obvious that this ideal separation surface, in a channel such as 37 comprised between two adjacent blades of the turbine wheel, advances from the inlet to the outlet of the channel 37, during the turbine rotation, when this channel moves away from the partition 27. The partition 31 must therefore be staggered forwardly of the partition 27 to such an extent that the boundary plane 36 reaches the channel outlet 37 as soon as the latter registers with the sector area 35. Likewise, the partition 32 must be staggered forwardly of the partition 28, so that the hot gas entering the channel 37 behind the relatively cold air as soon as the channel 37 moves past the partition 28, can reach the channel outlet as soon as the channel passes the partition 32. Degradation of the thermodynamic cycle, which would result from mixing hot and cold flows is thus avoided. The best positions of partitions 31 and 32 in relation to partitions 27 and 28 can be determined by the thermodynamic and fluid mechanics analysis according to the skill of the art.

It should be noted that the direct linking conduit 29 comprises, between the compressor outlet 6b and the turbine inlet 7b, neither diffuser, nor volute chambers, nor distributor. As already indicated above, this arrangement makes it possible to eliminate losses which would result from successive conversions of kinetic energy into pressure and vice versa. This is made possible by the fact that, in a gas turbine unit of the radialflow type with a free shaft line as shown, the outlet conditions of the compressor wheel blading are, by construction, adapted to the inlet conditions of the turbine wheel blading.

In the embodiment of FIG. 6, in which the elements performing the same functions as in FIG. are designated by the same reference numbers plus the suffix c, the compressor comprises, upstream of the centrifugal wheel 60, an axial flow stage, the rotor 38 of which is supported by the shaft line 8c. The air admitted from the outside at 12c is compressed in the axial stage comprising the rotor 38 and the straightening vanes 39, then-in the wheel 60 which delivers it at its periphery, at 26c and 29c at the total pressure appropriate for supplying the furnace 150, the turbine wheel 70 and the low pressure turbine 230. This total pressure is dictated by the operating characteristics of the gas turbine unit. Therefore if the turbines and the furnace are identical to those of FIG. 5, then the compressor comprising the axial flow stage 38, 39 and the centrifugal wheel 6c will have to deliver the same compression ratio as the single radial centrifugal wheel 6b shown in the said FIG. 5. However, the static pressure at the periphery of the wheel 60 will be greater, which will improve the flow of the cooling air in the wheel 70, as was explained hereinbefore.

FIG. 7, in which the elements performing-the same functions as in FIG. 5b are designated by the same references plus the suffix d, shows an embodiment in which the blades 40 of the compressor wheel 6d are backwardly curved, which as is known also increases the static pressure at the periphery of the wheel for the same compression ratio.

It should be pointed out that the increase in the static pressure, for the same total pressure at the outlet of the centrifugal wheel, may lead to a modification in the design of the diffuser (volute chamber such as 13d and fixed blading 26c or 26d) so that the air enters the furnace at the prescribed velocity and static pressure. As a result of this slight modification, the hot gas flow will remain unchanged.

In FIG. 8, where the elements performing the same functions as in FIG. 6 are designated by the same references plus the suffix e, the bladings 41 of the centrifugal wheel and 42 of the centripetal wheel extend radially beyond a disc-shaped rotatable partition member 43 on either side of which they are in back toback relation. "The annular spacings 44 contained between the outer portions of these bladings is occupied, in the sector contained between the diffuser 26e and the straightening vanes 19c, by a sector shaped stationary partition member 45 which extends radially outwards between the said diffuser 26e and the said straightening vanes l9e. On the remainderof its circumference, that is to say along the sector occupied by the conduits 29c and 29d in FIGS. 6 and 7, the annular space 44 remains empty and is crossed by the cooling air which passes directly from the blading 41 to the blading 42. The direct communication conduit between these bladings is constituted by the said sector of the annular space 44 and is limited externally by a wall 46 forming a portion of a cylinder in which the bladings 41, 42 rotate with slight play.

In a modification, the conduit is limited externally by a wall such as 29e (shown by dash lines) extending radially beyond the bladings 41, 42. The cooling air then passes partly through the space 44 and partly through the portion 44 of the conduit located radially outside the said space.

FIG. 9 shows how the invention can be applied to a gas turbine unit of the axial-flow type.

In FIG. 9, the elements performing the same functions as in FIGS. 5 to 8 are designated by the same reference numbers plus the suffixf. It can be seen at 6f an axial-flow compressor wheel which can be subsonic or supersonic, at 26fthe guide vanes of the compressor,

. at 19f the distributor of a driving turbine for the compressor, which receives hot gas from the furnace 15f and feeds a sector area of the axial-flow turbine wheel 7f. The hot gas discharged therefrom is led through a conduit 21f to the distributor 22f of a power turbine, and therefrom to the wheel 23f of the same which is also an axial-flow turbine wheel. The gas emerging from the power turbine is discharged to the atmosphere through a conduit 25f. Partitions not shown, similar to the partitions 27 and 28 of FIGS. 5a and 5b, define a direct linking sector conduit 29f between the compressor outlet 6f and the turbine inlet 7f. Further partitions not shown, similar to the partitions 31 and 32 of FIG. 5a, define an air discharge channel 33f. As in FIGS. 5, 5a and 5b, the air discharged into an outlet sector region of the compressor 6f, which is out of register with the sector conduit 29f, is led to the furnace 15f, whereas the air discharged into the outlet sector region which is in register with the sector conduit 29f is directly fed to the corresponding inlet sector region of the turbine 7f. The partitions defining the discharge conduit 33f are staggered forwardly, in the direction of rotation of the turbine, in relation to the partitions defining the conduit 29f. Here again, air passing through the sector conduit 29fis directly discharged by the compressor into the turbine inlet without passing throughguide vanes or a distributor. The layout of the compressor and turbine and their dimensioning parameters, in particular the pressure load factor and reaction degree of the compressor 6f and the reaction degree of the turbine 7f, are chosen so that the flow conditions at the outlet of the compressor rotor blading are adapted to the flow conditions at the inlet the turbine rotor blading as known in the art.

FIG. 10 shows how the invention can be applied by the low-pressure compressor, which feeds the highpressure compressor which is driven by the said turbine. In FIG. 10, the elements performing the same functions as in FIGS. to 9 are designated by the same reference numbers plus the suffix g. The high-pressure compressor 6g and the high-pressure turbine 7g are of the radial-flow type, and arranged like the compressor 6b and the turbine 7b of the FIG. 5, with the direct linking conduit 29g in the form ofa segment ofa torus. The shaft 24g of the turbine 23g drives, in addition to the receiving device not shown, a low-pressure compressor 47 which draws in air from atmosphere at 48, compresses and discharges the air through guide vanes 49 into a volute chamber 41 communicating through a conduit 51 with the inlet 12g of the high-pressure compressor 6g. The discharge conduit 33g for the air having cooled the turbine 7g does not lead to open air as in the preceeding Figures, but rejoins the conduit 51. This cooling air is thus mixed to the air discharged by the low-pressure compressor 47 to feed the high-pressure compressor 63. The mixture can be cooled in a known way, upstream of the high-pressure compressor, through a device shown by broken lines at 52.

The embodiment of FIG. lll differs solely from the embodiment of FIG. in an arrangement known per se andconsisting in heating the air discharged into the furnace by the high-pressure compressor, by means of a heat exchange with the exhaust gases of the low-pressure turbine. In FIG. 11, the elements performing the same functions as in FIG. 10 are designated by the same reference numbers plus the suffix h. Here again, the high-temperature high-pressure turbine wheel 7h is cooled by passing, during its rotation, into an region which receives directly through the conduit 29h a portion of the flow of the air discharged by the high pressure compressor 6h, then the partial flow rejoins through the conduit 33h the air discharged by the lowpressure compressor 47h into the high-pressure compressor, and the mixture can be cooled at 52h. However, the air discharged by the compressor 7hrtowards the furnace h through the discharge volute chamber 1312 and the conduit 14h, does not directly lead to that furnace but passes through a heat exchanger 53 and is thereafter sent through a conduit 54 to the furnace 15h. The discharge conduit h of the low-pressure turbine 23h does not directly lead to the atmosphere, but passes into the exchanger 53 where it is put in heat exchange relation, as schematically shown at 55, with the air emerging from the conduit 14h and forwarded to the conduit 54. It can be seen that this known arrangement does not at all affect the cooling of the turbine 7h, since the cooling air does not pass through the exchanger.

It will be appreciated that the embodiments as described are only examples and could be modified, notably by substitution of technical equivalents, without thereby departing from the spirit of the invention as defined in the appending claims. In particular,

the turbine could comprise more than one of the cold flow feed regions, for example two sector areas arranged symmetrically to the turbine axis.

We claim: I

1. A gas turbine plant comprising an air compressor including a compressor rotor'carrying acompressor outlet blading ;otatable in a circular path; stationary diffuser means for collecting air discharged from said outlet blading and for converting kinetic energy of said air into pressure energy, the inlet of said diffuser means extending over only a limited sector of said path with the remaining sector of said path disposed outside said inlet; furnace means connected to the exit of the diffuser means for receiving the air under pressure therefrom to generate hot gas under pressure; a gas turbine including a turbine rotor integral with the compressor rotor and carrying a plurality of blades rotatable in a circular path; means for feeding hot gas from said furnace means to the turbine, said means including a stationary distributor blading having an outlet which extends over only a limited sector of the last-mentioned circular path with the remaining sector of said path disposed outside said outlet; and conduit means bypassing both said furnace means and said diffuser means and connecting directly the compressor outlet blading and the turbine rotor over said remaining sectors of the respective circular paths, said conduit means being adapted to deliver air from said compressor outlet blading to the turbine rotor without substantial change in the temperature and kinetic energy of said air.

2. A gas turbine plant comprising an air compressor including a rotor carrying a centrifugal outlet blading;.

stationary diffuser means having an inlet which extends around only a sector of the periphery of said centrifugal outlet blading for collecting a part of the air discharged I from said blading and for converting kinetic energy of said air into pressure energy, the remainder of the periphery of said outlet blade being disposed outside said inlet; furnace means connected to the exit of said diffuser means for receiving the air under pressure to generate hot gas under pressure; a gas turbine including a rotor provided with a centripetal blading, said rotor being integral with said compressor rotor; a stationary distributor blading connected to the exit of said furnace means for feeding hot gas to said centripetal blading, said distributor blading having an outlet extending only around a sector of the peripheryof said centripetal blading with the remainder of said periphery disposed outside said outlet; and conduit means bypassing both said furnace means and said diffuser means and connecting directly the peripheral portions of said centrifugal outlet blading and of said centripetal blading which are respectively outside said diffuser inlet and said distributor blading outlet, said conduit means being adapted to deliver air from said centrifugal outlet blading to said centripetal blading without substantial change in the temperature and kinetic energy of said air.

3. A gas turbine plant according to claim 2 wherein said diffuser inlet and said distributor outlet arearrangecl side by side and said conduit means comprises a wall member of substantially circular shape arranged to cover the peripheral portions of said centrifugal outlet blading and of said centripetal blading which are respectively outside said diffuser inlet and said distributor outlet.

4. A gas turbine plant comprising an air compressor including a rotor carrying a centrifugal outlet blading;

stationary diffuser means having an inlet provided with guide vanes and a volute chamber, said inlet extending around only a sector of the periphery of said centrifugal outlet blading for collecting a part of the air discharged from said blading and for converting kinetic energy of said air into pressure energy; furnace means connected to the exit of said diffuser means for receiving the air under pressure to generate hot gas under pressure; a gas turbine including a rotor provided with a centripetal blading, said rotor being integral with said compressor rotor; a stationary distributor blading for feeding hot gas to said centripetal blading, said distributor blading having an outlet extending only around a sector of the periphery of said centripetal blading; a further volute chamber surrounding said distributor and connected to the exit of said furnace means; and conduit means bypassing both said furnace means and said diffuser means and connecting directly the peripheral portions of said centrifugal outlet blading and said centripetal blading which are respectively outside said diffuser'inlet and said distributor blading outlet; said conduit means having the form of a segment of torus arranged to cover the peripheral portions of said centrifugal outlet blading and said centripetal blading which are respectively outside said diffuser inlet and said distributor outlet, said conduit means being adapted to deliver air from the compressor outlet blading to said centripetal blading without substantial change in the temperature and kinetic energy of said air.

5. A gas turbine plant according to claim 2 comprising further a stationary outlet nozzle of generally circular shape arranged coaxially with respect to said centripetal blading for receiving the effluent from said blading and radial partitions in said nozzle adapted to separate said nozzle into two sectors which collects respectively and separately the hot gases and the air discharged from said centripetal blading.

6. A gas turbine plant according to claim 2 comprising further a stationary outlet nozzle of generally circular shape arranged coaxially with respect to said centripetal blading for receiving the effluent from said blading and two radial partitions in said nozzle for separating said nozzle into two sectors situated in forward staggered relation to the corresponding sectors of the distributor blading so that said nozzle sectors collect respectively'and separately the hot gases and the air discharged from said centripetal blading.

7. A gas turbine plant according to claim 5 comprising further: a low-pressure gas turbine mechanically independent from the first named turbine; conduit means connected to the hot gas-collecting sector of said nozzle for leading said gases to said low-pressure turbine; and other conduit means connected to the air collecting sector of the nozzle for exhausting said air into the atmosphere.

8. A gas turbine plant according to claim 5 comprising further: a second gas turbine mechanically independent from the first-named turbine; a second air compressor coupled with said second turbine so as to be driven by it; conduit means connected to said hot gascollecting sector of said nozzle for feeding said gases to the second turbine; and other conduit means adapted to receive the air issued from said second air compressor and from said air collecting sector of said nozzle and for feeding the whole of the air to the suction side of the first-named air compressor.

9. A gas turbine plant comprising an air compressor including a compressor rotor carrying a compressor centrifugal outlet blading; means for subdividing the air at great velocity issuing from the periphery of said centrifugal blading into a first air stream and a second air stream; a gas turbine coupled in driving relation with said compressor rotor and including a turbine rotor having uniformly spaced blades; stationary diffuser means associated with said centrifugal outlet blading so as to be fed only with the first air stream and to convert the kinetic energy of said stream into pressure energy; furnace means connected to the exit of the diffuser means for receiving the first air stream under pressure to generate hot gas under pressure; means including a stationary distributor blading for feeding some of said turbine rotor blades at a time with hot gas flowing from said furnace means; and conduit means bypassing said furnace means and said distributor blading for feeding the remaining turbine rotor blades at that time directly with the second air stream, said conduit means being adapted to leave substantially constant the temperature and the kinetic energy of said second stream.

10. A gas turbine plant according to claim 9 wherein the turbine rotor blades are centripetal and said conduit means are arranged to lead the second stream of air to the periphery of said turbine rotor.

11. A gas turbine plant according to claim 9 further comprising exhaust nozzle means arranged on the exhaust side of the turbine rotor and including two radial partitions defining two separate nozzle sectors and having angular positions adapted to feed one sector with hot gas and the other with air flowing from the rotor.

12. A gas turbine plant according to claim 9 whereinv the turbine rotor blades are centripetal and said conduit means are arranged to lead the second stream of air to the periphery of said turbine rotor; and further comprising exhaust nozzle means arranged on the exhaust side of the turbine rotor and including two radial partitions defining two separate nozzle sectors and havingangular positions adapted to feed one sector with hot gas and the other with air flowing from the rotor.

13. A gas turbine plant according to claim 9 wherein the turbine rotor blades are centripetal and said conduit means are arranged to lead the second stream of air to the periphery of said turbine rotor; and further comprising exhaust nozzle means arranged on the exhaust side of the turbine rotor and including two radial partitions defining two separate sectors arranged in forward staggered relation in the direction of rotor rotation to the groups of turbine rotor blades connected at a time respectively by the hot gas and second air stream so that said sectors collect respectively and separately the hot gases and the air discharged from said groups of turbine rotor blades.

14. A gas turbine plant according to claim 2 comprising means for producing, at the peripheral exit of the centrifugal outlet blading, a static pressure higher than the static pressure produced at the peripheral exit of a centrifugal compressor blading having radial tip blades and delivering a same compression ratio as said centrifugal outlet blading.

15. A gas turbine plant according to claim 14 wherein the compressor rotor and the turbine rotor form a free running shaft unit.

16. A gas turbine plant according to claim 14 wherein the compressor rotor comprises an axial-flow compression blading mounted upstream of the centrifugal outlet blading.

with partition means between them, and the conduit means is formed at least partly through the partition means.

21. A gas turbine plant according to claim 20 wherein the air compressor and gas turbine comprise a disc-shaped rotatable partition member, means mounting the centrifugal and centripetal bladings in back-to back relation on either side of said rotatable member, said centrifugal and centripetal bladings having outer portions extending radially beyond said rotatable member and defining an annular spacing between said outer portions, and a sector shaped stationary partition member extending along a sector of said annular spacing to divide the inlet of the diffuser means from the outlet of the distributor blading, whereas said outer portions of the centrifugal and centripetal bladings are in free communication along the remainder of said annular spacing. 

1. A gas turbine plant comprising an air compressor including a compressor rotor carrying a compressor outlet blading rotatable in a circular path; stationary diffuser means for collecting air discharged from said outlet blading and for converting kinetic energy of said air into pressure energy, the inlet of said diffuser means extending over only a limited sector of said path with the remaining sector of said path disposed outside said inlet; furnace means connected to the exit of the diffuser means for receiving the air under pressure therefrom to generate hot gas under pressure; a gas turbine including a turbine rotor integral with the compressor rotor and carrying a plurality of blades rotatable in a circular path; means for feeding hot gas from said furnace means to the turbine, said means including a stationary distributor blading having an outlet which extends over only a limited sector of the last-mentioned circular path with the remaining sector of said path disposed outside said outlet; and conduit means bypassing both said furnace means and said diffuser means and connecting directly the compressor outlet blading and the turbine rotor over said remaining sectors of the respective circular paths, said conduit means being adapted to deliver air from said compressor outlet blading to the turbine rotor without substantial change in the temperature and kinetic energy of said air.
 2. A gas turbine plant comprising an air compressor including a rotor carrying a centrifugal outlet blading; stationary diffuser means having an inlet which extends around only a sector of the periphery of said centrifugal outlet blading for collecting a part of the air discharged from said blading and for converting kinetic energy of said air into pressure energy, the remainder of the periphery of said outlet blade being disposed outside said inlet; furnace means connected to the exit of said diffuser means for receiving the air under pressure to generate hot gas under pressure; a gas turbine including a rotor provided with a centripetal blading, said rotor being integral with said compressor rotor; a stationary distributor blading connected to the exit of said furnace means for feeding hot gas to said centripetal blading, said distributor blading having an outlet extending only around a sector of the periphery of said centripetal blading with the remainder of said periphery disposed outside said outlet; and conduit means bypassing both said furnace means and said diffuser means and connecting directly the peripheral portions of said centrifugal outlet blading and of said centripetal blading which are respectively outside said diffuser inlet and said distributor blading outlet, said conduit means being adapted to deliver air from said centrifugal outlet blading to said centripetal blading without substantial change in the temperature and kinetic energy of said air.
 3. A gas turbine plant according to claim 2 wherein said diffuser inlet and said distributor outlet are arranged side by side and said conduit means comprises a wall member of substantially circular shape arranged to cover the peripheral portions of said centrifugal outlet blading and of said centripetal blading which are respectively outside said diffuser inlet and said distributor outlet.
 4. A gas turbine plant comprising an air compressor including a rotor carrying a centrifugal outlet blading; stationary diffuser means having an inlet provideD with guide vanes and a volute chamber, said inlet extending around only a sector of the periphery of said centrifugal outlet blading for collecting a part of the air discharged from said blading and for converting kinetic energy of said air into pressure energy; furnace means connected to the exit of said diffuser means for receiving the air under pressure to generate hot gas under pressure; a gas turbine including a rotor provided with a centripetal blading, said rotor being integral with said compressor rotor; a stationary distributor blading for feeding hot gas to said centripetal blading, said distributor blading having an outlet extending only around a sector of the periphery of said centripetal blading; a further volute chamber surrounding said distributor and connected to the exit of said furnace means; and conduit means bypassing both said furnace means and said diffuser means and connecting directly the peripheral portions of said centrifugal outlet blading and said centripetal blading which are respectively outside said diffuser inlet and said distributor blading outlet; said conduit means having the form of a segment of torus arranged to cover the peripheral portions of said centrifugal outlet blading and said centripetal blading which are respectively outside said diffuser inlet and said distributor outlet, said conduit means being adapted to deliver air from the compressor outlet blading to said centripetal blading without substantial change in the temperature and kinetic energy of said air.
 5. A gas turbine plant according to claim 2 comprising further a stationary outlet nozzle of generally circular shape arranged coaxially with respect to said centripetal blading for receiving the effluent from said blading and radial partitions in said nozzle adapted to separate said nozzle into two sectors which collects respectively and separately the hot gases and the air discharged from said centripetal blading.
 6. A gas turbine plant according to claim 2 comprising further a stationary outlet nozzle of generally circular shape arranged coaxially with respect to said centripetal blading for receiving the effluent from said blading and two radial partitions in said nozzle for separating said nozzle into two sectors situated in forward staggered relation to the corresponding sectors of the distributor blading so that said nozzle sectors collect respectively and separately the hot gases and the air discharged from said centripetal blading.
 7. A gas turbine plant according to claim 5 comprising further: a low-pressure gas turbine mechanically independent from the first named turbine; conduit means connected to the hot gas-collecting sector of said nozzle for leading said gases to said low-pressure turbine; and other conduit means connected to the air collecting sector of the nozzle for exhausting said air into the atmosphere.
 8. A gas turbine plant according to claim 5 comprising further: a second gas turbine mechanically independent from the first-named turbine; a second air compressor coupled with said second turbine so as to be driven by it; conduit means connected to said hot gas-collecting sector of said nozzle for feeding said gases to the second turbine; and other conduit means adapted to receive the air issued from said second air compressor and from said air collecting sector of said nozzle and for feeding the whole of the air to the suction side of the first-named air compressor.
 9. A gas turbine plant comprising an air compressor including a compressor rotor carrying a compressor centrifugal outlet blading; means for subdividing the air at great velocity issuing from the periphery of said centrifugal blading into a first air stream and a second air stream; a gas turbine coupled in driving relation with said compressor rotor and including a turbine rotor having uniformly spaced blades; stationary diffuser means associated with said centrifugal outlet blading so as to be fed only with the first air stream and to convert the kinetic energy of said stReam into pressure energy; furnace means connected to the exit of the diffuser means for receiving the first air stream under pressure to generate hot gas under pressure; means including a stationary distributor blading for feeding some of said turbine rotor blades at a time with hot gas flowing from said furnace means; and conduit means bypassing said furnace means and said distributor blading for feeding the remaining turbine rotor blades at that time directly with the second air stream, said conduit means being adapted to leave substantially constant the temperature and the kinetic energy of said second stream.
 10. A gas turbine plant according to claim 9 wherein the turbine rotor blades are centripetal and said conduit means are arranged to lead the second stream of air to the periphery of said turbine rotor.
 11. A gas turbine plant according to claim 9 further comprising exhaust nozzle means arranged on the exhaust side of the turbine rotor and including two radial partitions defining two separate nozzle sectors and having angular positions adapted to feed one sector with hot gas and the other with air flowing from the rotor.
 12. A gas turbine plant according to claim 9 wherein the turbine rotor blades are centripetal and said conduit means are arranged to lead the second stream of air to the periphery of said turbine rotor; and further comprising exhaust nozzle means arranged on the exhaust side of the turbine rotor and including two radial partitions defining two separate nozzle sectors and having angular positions adapted to feed one sector with hot gas and the other with air flowing from the rotor.
 13. A gas turbine plant according to claim 9 wherein the turbine rotor blades are centripetal and said conduit means are arranged to lead the second stream of air to the periphery of said turbine rotor; and further comprising exhaust nozzle means arranged on the exhaust side of the turbine rotor and including two radial partitions defining two separate sectors arranged in forward staggered relation in the direction of rotor rotation to the groups of turbine rotor blades connected at a time respectively by the hot gas and second air stream so that said sectors collect respectively and separately the hot gases and the air discharged from said groups of turbine rotor blades.
 14. A gas turbine plant according to claim 2 comprising means for producing, at the peripheral exit of the centrifugal outlet blading, a static pressure higher than the static pressure produced at the peripheral exit of a centrifugal compressor blading having radial tip blades and delivering a same compression ratio as said centrifugal outlet blading.
 15. A gas turbine plant according to claim 14 wherein the compressor rotor and the turbine rotor form a free running shaft unit.
 16. A gas turbine plant according to claim 14 wherein the compressor rotor comprises an axial-flow compression blading mounted upstream of the centrifugal outlet blading.
 17. A gas turbine plant according to claim 16 wherein the compressor rotor and the turbine rotor form a free running shaft unit.
 18. A gas turbine plant according to claim 14 wherein the centrifugal outlet blading has backwardly curved blades.
 19. A gas turbine plant according to claim 18 wherein the compressor rotor and the turbine rotor form a free running shaft unit.
 20. A gas turbine plant according to claim 2 wherein the air compressor and gas turbine comprise an integral unit comprising the centrifugal outlet blading and the centripetal blading arranged in back-to-back relation with partition means between them, and the conduit means is formed at least partly through the partition means.
 21. A gas turbine plant according to claim 20 wherein the air compressor and gas turbine comprise a disc-shaped rotatable partition member, means mounting the centrifugal and centripetal bladings in back-to-back relation on either side of said rotatable member, said centrifugal and centripetal bladings having outer portions extending radially beYond said rotatable member and defining an annular spacing between said outer portions, and a sector shaped stationary partition member extending along a sector of said annular spacing to divide the inlet of the diffuser means from the outlet of the distributor blading, whereas said outer portions of the centrifugal and centripetal bladings are in free communication along the remainder of said annular spacing. 